Season 27 of "Big Brother" premieres Thursday. Meet this year's houseguest and see how to watch the CBS original series.

Rachel Reilly, winner of Big Brother 13, was unveiled as the "mystery houseguest" competing again this summer on season 27.CBS had been teasing a secret player all week and dropping clues on social media as to who it was.

Popular reality show “Big Brother” premiered this week, featuring two Texas residents who say they are up for the challenge.

Big Brother follows a group of people living together in a house outfitted with more than 100 cameras and 100 microphones, recording their every move 24 hours a day. Each week, someone will be voted out of the house, with the last remaining Houseguest receiving the grand prize of $750,000.

Not even The Masked Singer fandom is that good at figuring out identities that quickly, so props to the Big Brother fans who figured all of this out with so little information in less than a day. CBS may want to uses masks next time.

Julie Chen Moonves returns to host Big Brother Season 27, which premieres with a 90-minute episode on Thursday, July 10 at 8 p.m. ET on CBS. A second 90-minute episode will follow on Sunday, July 13 at 8 p.m. ET. RELATED: ‘Survivor 50’ Cast Photos: All The Castaways Confirmed For CBS Competition

The cast of "Big Brother" Season 27 has been revealed — with one "Mystery Player" set to make a surprise entrance.